powerEdge r720 not start by switch on/off or when reboot

I bought a used powerEdge r720 for my own training . All firmwares are up to date. The problem is that I can't start it with the on/off button. To start it, you have to disconnect the power supplies, remove the battery from the CMOS memory to clear the bios, wait 1 minute, put the battery back in and connect the power supply. It starts after configuring the bios, same problem, it doesn't restart! Does anyone know how to solve this?

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